Securities and Exchange Commission
Washington, D. C. 20549
Schedule 13G
Under the Securities Exchange Act of 1934
(Amendment No. )
Input/Output Inc
Common Stock
CUSIP Number 457652105
Date of Event Which Requires Filing of this Statement: December 31, 2006
Check the appropriate box to designate the rule pursuant to which this
Schedule is filed:
[ X ] Rule 13d-1(b)
[ ] Rule 13d-1(c)
[ ] Rule 13d-1(d)
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CUSIP No. 457652105
1) Name of reporting person:
ClearBridge Advisors, LLC
Tax Identification No.:
01-0846058
2) Check the appropriate box if a member of a group:
a) x
b) n/a
3) SEC use only
4) Place of organization:
DE
Number of shares beneficially owned by each reporting person with:
5) Sole voting power: - 0 -
6) Shared voting power: 5,780,460
7) Sole dispositive power: - 0 -
8) Shared dispositive power: 5,921,291
9) Aggregate amount beneficially owned by each reporting person:
5,921,291
10) Check if the aggregate amount in row (9) excludes certain shares:
n/a
11) Percent of class represented by amount in row (9):
7.41%
12) Type of reporting person:
IA
CUSIP No. 457652105
1) Name of reporting person:
ClearBridge Asset Management, Inc.
Tax Identification No.:
13-3440564
2) Check the appropriate box if a member of a group:
a) x
b) n/a
3) SEC use only
4) Place of organization:
DE
Number of shares beneficially owned by each reporting person with:
5) Sole voting power: - 0 -
6) Shared voting power:
7) Sole dispositive power: - 0 -
8) Shared dispositive power: 970
9) Aggregate amount beneficially owned by each reporting person:
970
10) Check if the aggregate amount in row (9) excludes certain shares:
n/a
11) Percent of class represented by amount in row (9):
0.00%
12) Type of reporting person:
IA
CUSIP No. 457652105
1) Name of reporting person:
Smith Barney Fund Management LLC
Tax Identification No.:
13-2616913
2) Check the appropriate box if a member of a group:
a) x
b) n/a
3) SEC use only
4) Place of organization:
DE
Number of shares beneficially owned by each reporting person with:
5) Sole voting power: - 0 -
6) Shared voting power: 14,400
7) Sole dispositive power: - 0 -
8) Shared dispositive power: 14,400
9) Aggregate amount beneficially owned by each reporting person:
14,400
10) Check if the aggregate amount in row (9) excludes certain shares:
n/a
11) Percent of class represented by amount in row (9):
0.02%
12) Type of reporting person:
IA
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Item 1a) Name of issuer:
Input/Output Inc
Item 1b) Address of issuer s principal executive offices:
2101 Citywest Blvd.
Building III Suite 400
Houston, TX 77042
Item 2a) Name of person filing:
ClearBridge Advisors, LLC
ClearBridge Asset Management, Inc.
Smith Barney Fund Management LLC
Item 2b) Address of principal business office:
399 Park Avenue
New York, NY 10022
Item 2c) Citizenship:
ClearBridge Advisors, LLC
Delaware Limited Liability Corporation
ClearBridge Asset Management, Inc.
Delaware Corporation
Smith Barney Fund Management LLC
Delaware Limited Liability Corporation
Item 2d) Title of class of securities:
Common Stock
Item 2e) CUSIP number: 457652105
Item 3) If this statement is filed pursuant to Rule 13d-1(b),
or 13d 2(b), check whether the person filing is a:
(a) [ ] Broker or dealer under Section 15 of the Act.
(b) [ ] Bank as defined in Section 3(a)(6) of the Act.
(c) [ ] Insurance Company as defined in Section 3(a)(6) of the Act.
(d) [ ] Investment Company registered under Section 8 of
the Investment Company Act.
(e) [ ] Investment Adviser registered under Section 203 of
the Investment Advisers Act of 1940.
(f) [ ] Employee Benefit Plan, Pension Fund which is subject
to ERISA of 1974 or Endowment Funds; see 240.13d-1(b)(ii)(F).
(g) [ ] Parent holding company, in accordance with 240.13d-1(b)(ii)(G),
(h) [X] Group, in accordance with 240.13d-1(b)(1)(ii)(J).
Item 4) Ownership:
(a) Amount beneficially owned: 5,936,661
(b) Percent of Class: 7.43%
(c) Number of shares as to which such person has:
(i) sole power to vote or to direct the vote:
0
(ii) shared power to vote or to direct the vote:
5,794,860
(iii) sole power to dispose or to direct the disposition of:
0
(iv) shared power to dispose or to direct the disposition of:
5,936,661
Item 5) Ownership of Five Percent or less of a class:
n/a
Item 6) Ownership of more than Five Percent on behalf of another person:
n/a
Item 7) Identification and classification of the subsidiary which
acquired the security being reported on by the parent
holding company:
n/a
Item 8) Identification and classification of members of the group:
ClearBridge Advisors, LLC
ClearBridge Asset Management, Inc.
Smith Barney Fund Management LLC
Item 9) Notice of dissolution of group:
n/a
Item 10) Certification:
By signing below I certify that, to the best of my knowledge and belief,
the securities referred to above were acquired and are held in the ordinary
course of business and were not acquired and are not held for the purpose
of or with the effect of changing or influencing the control of the
issuer of the securities and were not acquired and are not held in
connection with or as a participant in any transaction having that
purpose or effect.
Signature
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After reasonable inquiry and to the best of my knowledge and belief,
I certify that the information set forth in this statement is true,
complete and correct.
--------------------------------
Date February 8, 2007
ClearBridge Advisors, LLC
By: /s/ Leonard P. Larrabee
Leonard P. Larrabee, Secretary
ClearBridge Asset Management, Inc.
By: /s/ Leonard P. Larrabee
Leonard P. Larrabee, Secretary
Smith Barney Fund Management LLC
By: /s/ Michael Kocur
Michael Kocur, Assistant Secretary
Exhibit A
Joint Filing Agreement
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This Joint Filing Agreement confirms the agreement by and among the
undersigned that the Schedule 13G is filed on behalf of (i) each member of
the group identified in Item 8 and (ii) the other reporting person(s)
identified in Item 6 that may be deemed to beneficially own more than
five percent of the issuer s outstanding equity securities.
ClearBridge Advisors, LLC
By: /s/ Leonard P. Larrabee
Leonard P. Larrabee, Secretary
ClearBridge Asset Management, Inc.
By: /s/ Leonard P. Larrabee
Leonard P. Larrabee, Secretary
Smith Barney Fund Management LLC
By: /s/ Michael Kocur
Michael Kocur, Assistant Secretary